U.S. patent application number 10/530509 was filed with the patent office on 2005-12-08 for plate fixing system.
Invention is credited to Baccelli, Christian, Mangione, Paolo.
Application Number | 20050273099 10/530509 |
Document ID | / |
Family ID | 32031846 |
Filed Date | 2005-12-08 |
United States Patent
Application |
20050273099 |
Kind Code |
A1 |
Baccelli, Christian ; et
al. |
December 8, 2005 |
Plate fixing system
Abstract
Disclosed is a system for immobilizing two vertebrae, which
system includes two screws, and elongated connecting member and two
fastening systems. Each fastening system includes a clamping member
and a fastening member consisting of a single ring-shaped piece
having a lateral wall around an axial passage. The wall includes a
first aperture for the clamping member and a second aperture
comprising a first portion and a second portion. The first portion
has a rim forming a bearing surface for the screw head. The second
portion provides a free passage for the screw head. The axial
passage can receive one end of the connecting member and the screw
head, whereby (a) the screw head can be freely inserted into the
axial passage of the fastening member and (B) the end of the
connecting member and the screw head are immobilized by actuating
the clamping member.
Inventors: |
Baccelli, Christian;
(Saucats, FR) ; Mangione, Paolo; (Pessac,
FR) |
Correspondence
Address: |
THE WEBB LAW FIRM, P.C.
700 KOPPERS BUILDING
436 SEVENTH AVENUE
PITTSBURGH
PA
15219
US
|
Family ID: |
32031846 |
Appl. No.: |
10/530509 |
Filed: |
April 6, 2005 |
PCT Filed: |
October 2, 2003 |
PCT NO: |
PCT/FR03/02890 |
Current U.S.
Class: |
606/261 ;
606/264; 606/266 |
Current CPC
Class: |
A61B 17/7037 20130101;
A61B 17/701 20130101 |
Class at
Publication: |
606/061 |
International
Class: |
A61B 017/70 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 7, 2002 |
FR |
0212397 |
Feb 28, 2003 |
FR |
0302503 |
Claims
1-6. (canceled)
7. A system for immobilizing two or more vertebrae, which system
comprises two or more screws, an elongate connecting member and two
or more fastening systems, wherein each screw comprises a screw
body and a screw head having the shape of a portion of a sphere
consisting of a first spherical surface portion between the screw
body and a diametral plane orthogonal to the axis of the screw body
and a second spherical surface portion; and each fastening system
comprises: a clamping member; and a fastening member formed in one
piece having the shape of a ring having a lateral wall around an
axial passage, said wall including a first aperture adapted to
receive and to cooperate with said clamping member and a second
aperture having a first portion and a second portion, said two
portions communicating with each other and being angularly offset
relative to the axis (Y, Y') of the fastening member, said first
portion having a diametral axis (Z, Z') substantially coinciding
with that of said first aperture and a rim forming a bearing
surface for said first spherical surface portion of the screw head,
said second portion of the second aperture allowing the screw head
to pass through it, said axial passage being adapted to receive at
least one end of said connecting member and said screw head,
whereby the screw head may be freely introduced into the axial
passage of the fastening member via said second portion of the
second aperture by rotating said fastening member, with the bearing
surface of the first portion of the second aperture made to face
the first spherical surface portion of the screw head and, by
activation of the clamping member, the end of the connecting member
and the screw head immobilized against rotation and against
movement in translation relative to said fastening member.
8. The immobilization system according to claim 7, wherein said
fastening system further comprises an intermediate member adapted
to be inserted into the axial passage of the fastening member and
having a first face adapted to be made to face the internal face of
the wall of the fastening member, a recess opening onto said first
face, forming a bearing surface for at least a portion of said
second spherical surface portion of the screw head, and a second
bearing face adapted to cooperate with the ends of the connecting
member whereby, when said intermediate member is inserted into the
axial passage of the connecting member, the clamping force produced
by the clamping member is transmitted to said intermediate member
via the end of the connecting member.
9. The immobilization system according to claim 7, wherein each end
of said connecting member has a substantially plane first face and
a second face including a longitudinal recess defining two inclined
bearing surfaces adapted to cooperate with the second spherical
surface portion of the screw head.
10. The immobilization system according to claim 8, wherein said
intermediate member has at each end a rib projecting from its first
face to cooperate with the end faces of said fastening member when
the intermediate member is engaged in the axial passage of the
fastening member.
11. The immobilization system according to claim 8, wherein each
end of the connecting member has a substantially plane first face
for cooperating with the clamping member and a second face defining
two substantially plane bearing surfaces for cooperating with the
second face of said intermediate member.
12. The immobilization system according to claim 10, wherein each
end of the connecting member has a substantially plane first face
for cooperating with the clamping member and a second face defining
two substantially plane bearing surfaces for cooperating with the
second face of said intermediate member.
13. The immobilization system according to claim 8, wherein said
connecting member has a circular cross section and said second face
of the intermediate member includes a bearing surface that has a
cross section in the shape of a circular arc adapted to receive an
end of said connecting member.
14. The immobilization system according to claim 10, wherein said
connecting member has a circular cross section and said second face
of the intermediate member includes a bearing surface that has a
cross section in the shape of a circular arc adapted to receive an
end of said connecting member.
Description
[0001] The present invention relates to a system for immobilizing
two or more vertebrae relative to each other.
[0002] To be more precise, the present invention relates to a
mechanical system that may be fitted by a surgeon to two or more
vertebrae of the vertebral column in order to immobilize the at
least two vertebrae relative to each other.
[0003] Systems of the above kind are known in the art. They
comprise two pedicular screws that are screwed into the pedicles of
the two vertebrae to be immobilized by an elongate member, usually
referred to as a plate, whose ends are fixed to the heads of the
two screws by mechanical fastening means so that the distance
between the heads of the screws, and therefore the distance between
the two vertebrae, remains fixed.
[0004] The screw heads are usually spherical in order to cooperate
with the corresponding fastening means to form a ball-joint system
allowing the plate to be fitted without applying stresses to the
screws, and therefore to the vertebrae into which they are fixed,
regardless of the relative direction of the two screws.
[0005] Clearly, one quality required of a system of the above kind
is that the fastening of the plate and the screws should be
sufficiently effective to be able to absorb the forces resulting
from movements of the patient fitted with the immobilization
system. Also, it is of course desirable for the system to be as
easy for the surgeon to fit as possible, and for fitting it to
require the shortest possible time on the operating table.
[0006] An object of the present invention is to provide a system of
the type referred to above for immobilizing two or more vertebrae
that constitutes a better response to the two conditions stated
above.
[0007] To achieve the above object, the system of the invention for
immobilizing two or more vertebrae comprises two or more screws, an
elongate connecting member and two or more fastening systems and is
characterized in that each screw comprises a screw body and a screw
head having the shape of a portion of a sphere consisting of a
first spherical surface portion between the screw body and a
diametral plane orthogonal to the axis of the screw body and a
second spherical surface portion; and
[0008] each fastening system comprises at least:
[0009] a clamping member; and
[0010] a fastening member formed in one piece having the shape of a
ring having a lateral wall around an axial passage, said wall
including a first aperture adapted to receive and to cooperate with
said clamping member and a second aperture having a first portion
and a second portion, said two portions communicating with each
other and being angularly offset relative to the axis (Y, Y') of
the fastening member, said first portion having a diametral axis
(Z, Z') substantially coinciding with that of said first aperture
and a rim forming a bearing surface for said first spherical
surface portion of the screw head, said second portion of the
second aperture allowing the screw head to pass through it, said
axial passage being adapted to receive at least one end of said
connecting member and said screw head, whereby the screw head may
be freely introduced into the axial passage of the fastening member
via said second portion of the second aperture by rotating said
fastening member, the bearing surface of the first portion of the
second aperture is made to face the first spherical surface portion
of the screw head and, by activation of the clamping member, the
end of the connecting member and the screw head are immobilized
against rotation and against movement in translation relative to
said fastening member.
[0011] Clearly, the system for fastening together the head of the
pedicular screw and the elongate connecting member is really
effective, because the clamping member presses the head of the
pedicular screw with an appropriate force onto the bearing surface
around the first portion of the second aperture, the axis of the
clamping member and the axis of the aperture comprising the bearing
surface substantially coinciding.
[0012] It is also clear that a fastening member that is made in one
piece has a number of advantages: firstly, this avoids the surgeon
needing to assemble a large number of parts under difficult
operating conditions; secondly, the one-piece ring may have a
smooth and regular exterior profile essentially free of asperities
that could damage the surrounding human tissue.
[0013] It is further clear that the above immobilizing system is
relatively easy to install since, after screwing the pedicular
screws into the pedicles of the two vertebrae to be immobilized,
the connecting member can easily be engaged over the head of each
screw, thanks to the second part of the second aperture, and since
it is also easy to lock the head of the screw into the fastening
member, as it is sufficient to pivot the fastening member and to
activate the clamping member.
[0014] In a preferred embodiment, said fastening system further
comprises an intermediate member adapted to be inserted into the
axial passage of the fastening member and having a first face
adapted to be made to face the internal face of the wall of the
fastening member, a recess opening onto said first face, forming a
bearing surface for at least a portion of said second spherical
surface portion of the screw head, and a second bearing face
adapted to cooperate with the ends of the connecting member
whereby, when said intermediate member is inserted into the axial
passage of the connecting member, the clamping force produced by
the clamping member is transmitted to said intermediate member via
the end of the connecting member.
[0015] It is clear that in this preferred embodiment the clamping
member clamps the head of the screw to the bearing surface via the
intermediate member. The presence of this intermediate member
enhances the quality of the contact between the intermediate
member, to which the clamping force produced by the clamping member
is applied, and the spherical head of the pedicular screw. In a
preferred embodiment of this variant, the intermediate member may
be premounted in the axial passage of the fastening member before
it is used. The presence of this member therefore does not make the
system for relative immobilization of vertebrae any more
complicated to use.
[0016] Other features and advantages of the invention become more
apparent on reading the following description of embodiments of the
invention given by way of non-limiting example. The description
refers to the appended drawings, in which:
[0017] FIG. 1 is a perspective view showing the immobilization
system fitted to two vertebrae;
[0018] FIG. 2 is an exploded view of the components of the
immobilization system;
[0019] FIG. 3 is a perspective view of the fastening member;
[0020] FIG. 4A is a top view of the fastening member;
[0021] FIG. 4B is a view in section taken along the line B-B in
FIG. 4A;
[0022] FIG. 4C is a view in section taken along the line C-C in
FIG. 4B;
[0023] FIG. 5 is a view in vertical section showing the fastening
together of a screw and the connecting member in a first embodiment
of the invention;
[0024] FIG. 6 is a perspective view of a first variant of the
intermediate member;
[0025] FIG. 7A is a top view of the FIG. 6 intermediate member;
[0026] FIG. 7B is a view in section taken along the line B-B in
FIG. 7A;
[0027] FIG. 7C is a view in section taken along the line C-C in
FIG. 7A;
[0028] FIG. 8A is a view in longitudinal section of a first variant
of the connecting member;
[0029] FIG. 8B is a bottom view of the FIG. 8A connecting
member;
[0030] FIG. 8C is a view in section taken along the line C-C in
FIG. 8A;
[0031] FIGS. 9A, 9B and 9C show the fastening together of a screw
and the connecting member in an improved embodiment of the
invention;
[0032] FIG. 10 is a perspective view of a second variant of the
securing system;
[0033] FIG. 11A is a perspective view of a variant of the
intermediate member;
[0034] FIG. 11B is a top view of the FIG. 11A intermediate
member;
[0035] FIG. 11C is a view in section taken along the line C-C in
FIG. 11B;
[0036] FIG. 11D is a view in section taken along the line D-D in
FIG. 11B; and
[0037] FIG. 12 is a view in elevation of the FIG. 10 variant.
[0038] The whole of the system for immobilizing two or more
vertebrae is described first with reference to FIG. 1, after it has
been fitted.
[0039] This figure shows a first vertebra V1 with its pedicle P1
and an adjacent second vertebra V2 with its pedicle P2. The
immobilizing system 10 comprises a first pedicular screw 12 screwed
into the pedicle P1, a second pedicular screw 14 screwed into the
pedicle P2, a first fastening system 16 associated with the
pedicular screw 12 and a second fastening system 18 associated with
the pedicular screw 14. The immobilizing system 10 finally
comprises an elongate connecting member 20 that is usually referred
to as a plate. As this figure shows, each end 20a, 20b of the
connecting member 20 is secured to the corresponding pedicular
screw 12, 14 by a fastening system 16, 18. It is therefore clear
that, by means of the connecting member 20, and by adjusting the
distance between the fastening systems 16 and 18, after installing
the screws 12 and 14, the surgeon can set a distance between the
vertebrae V1 and V2.
[0040] The various component parts of the immobilizing system are
described in more detail next with reference to FIG. 2. That figure
shows the pedicular screw 12, which has a longitudinal axis X-X', a
body 12a and a head 12b. The screw body 12a is preferably connected
to the head 12b by a flange 22. The screw head 12b has a
part-spherical surface divided by a diametral plane P perpendicular
to the axis X, X' into a first spherical surface portion 24 between
the plane P and the screw body 12a and a second spherical surface
portion 26. The second spherical surface portion 26 is limited by a
blind hole 38 of hexagonal or other shape adapted to receive a
screwing tool. The fastening system 16 essentially consists of a
fastening member 28, a clamping member 30 and, preferably but not
necessarily, an intermediate member 32.
[0041] The fastening member 28 has the general shape of a ring
consisting of a wall 34 whose internal face 34a is substantially a
circular cylinder of revolution about an axis Y-Y'. This wall 34 of
the member 28 has an axial passage 36 limited by the internal face
34a and two apertures 38 and 40 in the wall 34.
[0042] The first aperture 38 has a wall 38a that is tapped or
constitutes part of a bayonet system. The aperture 38 is adapted to
receive the clamping member 30, which has a portion 30a that is
threaded or constitutes part of a bayonet system and a head 41 with
a blind hole 42 for inserting a screwing or clamping tool, for
example. FIG. 2 also shows the elongate connecting member 20, which
has a substantially plane first face 34 adapted to cooperate with
the active portion 30a of the clamping member 30. The portion 20,
or at least each of its ends 20a and 20b, is adapted to be inserted
into the axial passage 36 of the fastening member 28.
[0043] The fastening member 28 is described in more detail next
with reference to FIGS. 3 and 4A to 4C. FIG. 3 shows the wall 34 of
this member with its cylindrical axial passage 36, its upper
aperture 38 adapted to receive the clamping member 30 and its
second aperture or lower aperture 40. FIG. 3 shows that the second
aperture 40 in fact consists of two portions 46 and 48 that
communicate with each other and are angularly offset relative to
the axis Y, Y' of the fastening member.
[0044] As shown better in FIGS. 4A and 4B, the first portion 46 of
the second aperture 40 is in the shape of a portion of a circle
(substantially a semicircle) whose axis Z-Z' coincides with the
axis of the first aperture 38. This aperture portion 46 has a
diameter D less than the diameter D' of the head 26 of the screw
12. The rim of the portion 46 of the aperture 40 constitutes a
bearing surface 50 in the shape of a portion of a spherical
surface, for example. The second aperture portion 48 is the shape
of a portion of a circle of diameter D1 that has an axis T, T'
offset at an angle a to the axis Z-Z'. The angle a may be 40
degrees. The diameter D1 of the second portion 48 of the aperture
40 is greater than the diameter D' of the head 26 of the screw 12.
The contour of the second aperture 40 consists in the intersection
of the circle portions corresponding to the aperture portions 46
and 48, of course. It is clear that the head 26 of the screw 12 may
be freely inserted into the axial passage 26 of the fastening
member 28 through the second part 48 of the aperture 40 when the
axis X, X' of the screw is lined up with the axis T, T' of the
aperture portion 48. If, however, the axis X, X' of the screw 12 is
lined up with the axis Z-Z' of the fastening member 28, after
inserting its head into the axial passage 36, the first spherical
surface portion 24 of that head comes into contact with the
spherical bearing surface 50, which "traps" the screw head in the
axial passage 36.
[0045] FIG. 5 shows the assembled first embodiment of immobilizing
device, i.e. the embodiment in which the fastening system does not
include the intermediate member 32. This figure shows the screw 12
inserted in the first portion 46 of the second aperture 40 of the
fastening member 28. The first spherical surface portion 24 of the
screw head 12b therefore bears on the bearing surface 50 of this
part of the aperture. In this embodiment, the second face 52 of the
end 20b of the connecting member 20 includes a longitudinal recess
54 that defines two inclined longitudinal bearing surfaces 56 and
58. When the end 20b of the connecting member 20 is inserted into
the axial passage 36 of the fastening member 28, the inclined
bearing surfaces 56 and 58 of the member 20 face the second
spherical surface portion 26 of the screw head 12b. When the
clamping member 30 is screwed into its tapped aperture 38, the
active face 30a is pressed against the plane face 44 of the member
20, which transmits the clamping force to the screw head 12b, which
is immobilized against rotation by the cooperation of the bearing
surfaces 50, 56 and 58. At the same time, this clamping immobilizes
the member 20 against movement in translation relative to the
fastening member 28.
[0046] In an improved embodiment of the immobilizing system, each
fastening system 16, 18 further comprises an intermediate member 32
that can be inserted into the axial passage 36 of the fastening
member 20.
[0047] A first preferred embodiment of the intermediate member 32
is described next with reference to FIGS. 6 and 7A to 7C. The
intermediate member has a first face 60 in the shape of a portion
of a cylindrical surface whose radius is substantially equal to
that of the axial passage 36 of the fastening member 28. A recess
62 described in more detail later is formed in this first face 60.
The second face 66 of the member 32 is substantially plane. The
member 32 preferably has a rib 68, 70 at each end. The ribs are
separated by an axial length L at least equal to the axial length
of the member 28.
[0048] As shown better in FIG. 7B, the recess 62 formed in the
member 32 has an active portion opening into the face 60 which
constitutes a frustoconical, or possibly spherical, bearing surface
64. To facilitate machining, the active portion of the recess 62 is
preferably extended by a circular part 72. It is also preferable if
the member 32 includes a longitudinal groove 74 in its median
longitudinal plane to enable it to deform elastically, as explained
later.
[0049] The intermediate member 32 is inserted into the axial
passage 36 in the fastening member 28 between the head 12b of the
screw 12 and the ends 20a of the connecting member 20. The function
of this part is to transmit the clamping force exerted by the
clamping member 30 on the upper face 44 of the connecting member 20
to the second spherical portion 26 of the screw head 12b, by virtue
of cooperation of the frustoconical bearing surface 64 of the
recess 62 in the member 32 with the second spherical surface
portion of the screw head 12b.
[0050] The particular shape of the connecting member 20 in the
improved embodiment is described with reference to FIGS. 8A, 8B and
8C. The member 20 still has a plane upper face 44 and its second
face 80 is also plane and includes an axial recess 82 such that
this face 80 defines two longitudinal plane bearing surfaces 84 and
86. As explained later, these bearing surfaces 84 and 86 bear on
the plane upper face 66 of the intermediate member 32.
[0051] The use of the improved embodiment of the immobilization
system is described next with reference to FIGS. 9A, 9B, 9C.
[0052] It should first be pointed out that the intermediate member
32 is preferably premounted inside the axial passage 36 of the
fastening member and that the clamping member 30 is preferably
premounted on the fastening member.
[0053] After screwing the screws 12 and 14 into the pedicles of the
vertebrae to be immobilized, the surgeon fits the fastening members
28 over the heads 12b of the screws so that the axis T, T' of the
second portion 48 of the second aperture 40 is aligned with that of
the screw 12. The screw head 12b can pass freely through the
aperture portion 48 and penetrate partially into the axial passage
36. To be more precise, the head 12b is accommodated inside the
recess 62 of the intermediate member 32 which, at this stage, is
free to pivot about the longitudinal axis of the fastening member.
After carrying out this operation in respect of the screws 12 and
14, the surgeon fits the elongate connecting member 20 or, to be
more precise, the ends 20A and 20B thereof, which have already been
engaged in the fastening members 28.
[0054] When these operations have been completed, the surgeon turns
the fastening member 28 through the angle a about its longitudinal
axis to align the axis Z, Z' of the first portion 46 of the
aperture 40 with that of the screw 12 (see FIG. 9B). In this
position, the first spherical surface portion 24 of the screw head
12b bears on the bearing surface 50 of the fastening member. It
should be noted that, thanks to the ball-joint system formed by the
screw head 12b and the spherical or conical bearing surfaces 50 of
the portions 28, 64 of the intermediate member, the angular
position of the elongate member 20 relative to the screws 12 and 14
may be adapted. When this operation has been completed, it suffices
for the surgeon to activate the clamping members 30 of the two
fastening members 28 to lock and immobilize the screw 12 and the
connecting member 20 onto the fastening member 28.
[0055] A variant of the improved embodiment of the invention is
described next with reference to FIGS. 10 to 12.
[0056] This variant differs from the embodiment already described
by virtue of the fact that the elongate connecting member 20' shown
in FIG. 10 is a circular cross-section rod. Obviously, the
intermediate member 32' shown in FIG. 10 must therefore be
modified.
[0057] Nevertheless, the screws 12, the screwing member 30 and the
fastening member 28 are not modified. They are therefore not
described again.
[0058] The variant of the intermediate member 32' is described with
more particular reference to FIGS. 11A to 1D. The member 32' has a
lower face 60' in the shape of a sector of a cylindrical surface
adapted to be pressed against the internal wall 34 of the axial
passage 36 in the fastening member 28. The lower face 60'
terminates at its ends in ribs 68' and 70' that have the same
function as the ribs 68 and 70.
[0059] A recess 62' in the lower face 60' of the member 32' has the
same function as the recess 62 and includes a frustoconical or
possibly spherical portion 64' adapted to bear on the spherical
head 12b of the screw 12.
[0060] The upper face 80' of the member 32' includes a
semicylindrical central bearing surface 82 conformed to receive the
connecting rod 20'. The central bearing surface 82 is extended at
both ends by semifrustoconical portions 84 and 86. The upper end of
the recess 62' opens into the central bearing surface 82, which
could equally well consist of two inclined plane surfaces
symmetrical about the median plane of the member 32'.
[0061] This embodiment is used in substantially the same way as the
embodiment shown in FIGS. 9A to 9D. The only difference is that the
end of the connecting rod 20' is pressed onto the bearing surface
82 by the screwing member 30.
[0062] It follows from the foregoing description of the use of the
securing system that the system facilitates installation, allows
the necessary adaptation of the direction of the connecting member
relative to the screws, and ensures secure and effective
immobilization of the screws and the connecting member.
* * * * *